The GABAergic system may play a significant role in the pathogenesis as well as in the pharmacological control of epilepsy and other brain diseases. Concentrations and rates of synthesis of GABA may reflect the activity of the GABAergic system. The goal of the proposed research is to develop quantitative single volume and multivolume 1H NMR methods for measuring brain gamma amino butyric acid (GABA) concentration and rates of synthesis in human brain. The methods will be applied in studies of human subjects to determine the precision of the measurement, the accuracy of the resonance assignment, and to measure the relaxation properties needed for GABA absolute quantitation. An animal model will be used to validate the NMR method by comparison with conventional chemical assay. The development of 1H NMR methods for measuring GABA will provide an important new tool for studying the human GABAergic system.